Solvent-free hydroamination of phenylacetylene by plasmonic gold nanoparticles coupled with a TiO2 2D photonic layer on nanotube arrays

Abstract

Hydroamination of alkynes provides a direct and atom-economical access to highly valuable organic nitrogen molecules. The design of a green catalytic process has attracted considerable attention. Here, we in situ tune a TiO₂ 2D photonic crystal (PC) layer on nanotube arrays (NTs) via the anodization process and selectively deposit small gold nanoparticles (Au NPs) with an average size of ∼7.5 nm into the 2D PC layer using the NaBH₄ reduction method. The as-prepared plasmonic samples show superior activity for the solvent-free hydroamination of phenylacetylene, illuminating with visible-light from both sides simultaneously. The 2D PC layer exhibits a much higher intensity ratio of anatase (004)/(101) than the NTs without the 2D PC layer and enhances the light-harvesting efficiency of plasmonic Au NPs, resulting in improved activity with a TON 294.8 and TOF 42.1 h⁻¹ of the imine product yield based on the Au molar content.